Yes, 2 dedicated coaches are for MAS, and it can be used by commuters traveling between MAS and ALLP and vice versa. It doesn't mean that, that coaches will be having 0 occupancy. Those coaches are meant for people who reserve in MAS-ALLP section. Also for unreserved sleeper ticket holders.
Train will be getting empty at PGT, bcoz from PGT, no one will prefer to take this train to ALLP. Any person who want to reach ALLP, can take SBC-ERS ICE, which comes 1hour after PGT and will reach ERS 1 hour before Dhanbad. Hence basically this train is not getting patronage because of its TT from PGT-ALLP. But in some scenarios, it will still run full